Gold Ore Research Articles

The Mineralogical and Geochemical Features of the Early Cretaceous Gold Ore Mineralization of the Eastern Flank of the Yana–Kolyma Orogenic Belt (Magadan Region, Russia)

The Mineralogical and Geochemical Features of the Early Cretaceous Gold Ore Mineralization of the Eastern Flank of the Yana–Kolyma Orogenic Belt (Magadan Region, Russia)

Epithermal Deposits of Kamchatka, Russia

The results of studying the epithermal deposits of Kamchatka, one of the most promising gold-mining provinces of the Russian Federation, are generalized. The deposits are divided into acid–sulfate (Ac-Sul) and adularia–sericite (Ad-Ser) types (Heald et al., 1987). The disadvantages of the scheme, which is the most popular in the English-language literature and is based on the sulfidation state of mineral parageneses in ores (LS, IS, and HS types), are shown. The classification that we proposed includes differences in mineral associations in circum–ore metasomatites, which are determined by the acidity–alkalinity and an oxidation state of mineral-forming fluids, and are clearly diagnosed at the first stages of studying the deposits. Kamchatka epithermal deposits of the Ad-Ser-type are associated with andesite volcanism of the volcanic belts. Gold ore associations are concentrated in quartz, carbonate–quartz, and adularia–quartz veins, as well as in sericitized metasomatites, which are replaced by argillizites and propylites towards the periphery. The Ad-Ser-type is characterized by combination with polysulfide (Pb, Zn) (Amethyst, Kumroch, Vilyuchinskoe deposits), sulfosalt (Ag, Sb, As, Bi, Sn) (Ozernovskoe, Baranyevskoe), and selenide (Ag, Se) (Amethyst, Asachinskoe, Rodnikovoe) assemblages. Low-fineness native gold (220–310‰) is typical of the early polysulfide assemblage. With an increase in the fugacity of Te and Se, the gold fineness increases to 510–740‰, and with the progressive activity of Sb, As and Bi and the formation of sulfosalt associations, it reaches 998‰. The homogenization temperatures of primary fluid inclusions in quartz from gold-bearing associations of the Ad-Ser-type are 260–250°C; the minerals crystallize from solutions containing no more than 3 wt % NaCl eq. Maletoyvayam, the only Ac-Sul-type deposit in Kamchatka, is localized in quartz, secondary quartzites, and alunite–sericite–kaolinite–quartz metasomatites. Gold-bearing parageneses indicate the leading role of selenium in mineral formation, contain high-fineness native gold, sulfoselenotellurides, tellurides, and selenides of Au, which crystallize from acidic fluids with salinity of 1–5 wt % NaCl eq. at temperatures of 290–175°C.

Using Kerosene as an Auxiliary Collector to Recover Gold from Refractory Gold Ore Based on Mineralogical Characteristics

Carbon–arsenic-bearing gold ore is a typical complex refractory gold resource. Traditionally, xanthate was often used as a flotation agent to separate gold minerals. But, in this paper, in order to reduce the cost of the agent, kerosene was used as an auxiliary collector, and the gold grade and recovery rate were increased by about 10 g/t and 5.5%, respectively. Through process mineralogy studies of the raw ore, it was found that the ore has an Au grade of 5.68 g/t, most of which is surrounded by sulfide ore, accounting for 79.46%. The main minerals are pyrite, arsenopyrite, and quartz, etc. Their content, shape, particle size distribution, and occurrence state were obtained via microscopic observation and statistical analysis. According to the results of process mineralogy, various flotation conditions were tested, including grinding fineness, kerosene dosage, collector dosage, foaming agent dosage, and the slurry pH value. The optimal chemical system and the process flow of “two roughing, three cleaning and two scavenging” were finally determined, and the concentrate product with a gold grade of 42.83 g/t and recovery of 91.02% was obtained, which verified the feasibility of the kerosene-assisted xanthate flotation of refractory gold.

Ore-Forming Fluids of Orogenic Gold Deposit In Tamilouw-Haya, Seram Island, Indonesia

The Tamilouw-Haya orogenic gold deposit is located in the southern arm of Seram Island, Indonesia, occupying Tehoru Metamorphic Complex. Gold mineralization is predominantly in the form of veins, stockwork, and breccia, although minor dissemination is slightly appeared in the rock float samples. Ore-mineral assemblages are dominated by native gold, pyrite, chalcopyrite, sphalerite, tetrahedrite-tennantite (sulfosalt), galena, pyrrhotite, marcasite, realgar, kalininite, and arsenopyrite. Covellite, hematite, goethite, and malachite appear as supergene minerals. High-grade gold ores in this area are generally found in quartz-carbonate veins with the main alteration processes involving silicification, carbonatization, and sericitic. The P-T history of the mineralization was revealed by fluid inclusions, and this study implies the depth of ore deposit and its evolution during mineralization. The primary fluid inclusions from three different types of quartz/quartz-carbonate veins in Tamilouw-Haya crystallized at the homogenization temperature (Th) of 240 °C to 340 °C, with a fluid salinity from 3.87 to 0.70 wt. % NaCl equivalent, and melting temperature (Tm) of -0.4 to -2.3 oC. The ore-forming fluids consist mainly of two-phase (VCO2+LH2O) liquid-rich aqueous inclusions, characterized by low to rich CO2, low salinity, and moderate temperature. There are three vein types as the ore-bearing fluids with precious metals and anomalous high basemetal contents. Quartz type 1- veins (V1); concordant veins, formed at a temperature of 240-307 oC with an average salinity of 1.8 wt. % NaCl equivalent. Quartz type 2- veins (V2) tend to cut the rock foliation which are formed at temperature range from 293-336 oC with the average salinity that shows a value of 2.4 wt. % NaCl equivalent. Meanwhile, type 3 quartz-carbonate veins (V3) are formed at the temperature range of 240-340 oC and the average salinity of 2.72 wt. % NaCl equivalent. These quartz-carbonate veins cut the wall-rock foliation, which is identified as the late stage and associated with ore deposition in Tamilouw-Haya. The gold deposit in Tamilouw-Haya is formed at a depth of about 5.5-9 km of paleosurface, and the pressure between 1.7-2.4 Kbar in epizonal to mesozonal zones. Keywords: Tamilouw-Haya, orogenic gold, fluid inclusion, microthermometry, ore-forming fluids

Study on the Effect of Cyanide Concentration on Gold Leaching Recovery in Ore at PT Indo Muro Kencana

Indonesia is a country that has abundant natural resources, including non-renewable natural resources such as various types of metals, natural gas, petroleum and others. Besides that, Indonesia also has an important role in supplying the world's gold raw materials. Therefore, it is necessary to develop technology and science in the mining industry, especially gold to increase process optimization and increase the added value of the mining products themselves. One of the gold extraction processes can be carried out hydrometallurgically using the cyanidation method using agitator leach, as was done at PT Indo Muro Kencana. Process optimization is carried out with various test work, such as leaching tests, by varying the operating parameters of the leaching. The results of the analysis show that the optimal cyanide concentration for leaching of PT Indo Muro Kencana's gold ore is 600 ppm by controlling the rate diffusion control.

Origin of Archean Pb isotope variability through open-system Paleoarchean crustal anatexis

Abstract Lead isotopic data imply that thorium and uranium were fractionated from one another in Earth’s early history; however, the origin of this fractionation is poorly understood. We report new in situ Pb isotope data from orthoclase in 144 granites sampled across the Archean Yilgarn craton (Western Australia) to characterize its Pb isotope variability and evolution. Granite Pb isotope compositions reveal three Pb sources, a mantle-derived Pb reservoir and two crustal Pb reservoirs, distinguished by their implied source 232Th/238U (κPb). High-κPb granites reflect sources with high 232Th/238U (~4.7) and are largely co-located with Eoarchean–Paleoarchean crust. The Pb isotope compositions of most granites, and those of volcanic-hosted massive sulfide (VHMS) and gold ores, define a mixing array between a mantle Pb source and a Th-rich Eoarchean–Paleoarchean source. Pb isotope modeling indicates that the high-κPb source rocks experienced Th/U fractionation at ca. 3.3 Ga. As Th/U fractionation in the Yilgarn craton must have occurred before Earth’s atmosphere was oxygenated, subaerial weathering cannot explain the apparent differences in their geochemical behavior. Instead, the high Th/U source reflects Eoarchean–Paleoarchean rocks that experienced prior high-temperature metamorphism, partial melting, and melt loss in the presence of a Th-sequestering mineral like monazite. Archean Pb isotope variability thus has its origins in open-system high-temperature metamorphic processes responsible for the differentiation and stabilization of Earth’s continental crust.

Oxidation of sulfide mineral and metal extraction analysis in the microwave-assisted roasting pretreatment of refractory gold ore

The recovery of gold from refractory ore could guarantee sustainable development in the gold industry. However, there are many challenges in the treatment of ore, such as environmental pollution and low recovery. In this regard, the current research focuses on the pretreatment of refractory gold ore and investigates the effect of microwave power, the role of additives, and water on the oxidation and decomposition of sulfide minerals. Pretreatment using microwave-assisted roasting with NaClO3 as an additive to the oxidizing agent is a new method of processing refractory gold ore. Oxidation was studied through sulfur and chlorine mass balance analysis and the degree of metal extraction from sulfide minerals. SEM analysis was carried out to complete the study of the phase change of compounds in the oxidation of mineral sulfides. Roasting of refractory gold ore with a composition of 180 kg NaClO3 and 180 kg water/ton ore reached a temperature of 470 °C at a microwave power of 400 watts for 30 minutes. Total oxidized sulfur reached 90.6%, while only 10.4 % of the sulfur was released, and chlorine release was 49.5%. In addition, water leaching was conducted to investigate the extraction rate of metals after roasting. The results showed that the water leaching extraction of Cu, Zn, Pb, and Fe reached 84.3%, 97.6%, 22.8%, and 8.4%, respectively. Applying microwaves with appropriate concentrations of additives and water resulted in high oxidation of sulfide minerals (>90%) and low sulfur emissions in roasting refractory gold ore with relatively low power, temperature, and time. Moreover, leaching this roasted gold ore resulted in gold extraction of 92.5%; however, leaching of refractory gold without pretreatment resulted in gold extraction of only 47.5%.

Experimenting with Dimethyl Sulfoxide to Leach Gold from a Colombian Artisanal Gold Ore

The diverse uses of gold and its crucial role in the global economy are growing, particularly during cycles of economic crises. The broad use of cyanide by conventional gold-mining companies and mercury by artisanal miners poses environmental and health concerns for local communities. This article introduces an innovative gold-leaching process using a non-toxic organic reagent, dimethyl sulfoxide (DMSO), a water-free lixiviant that extracts gold from ores/concentrates in combination with copper halides. The results of laboratory experiments using dimethyl sulfoxide and a sample of high-grade gold ore from Colombia show that 96.5% of the gold was extracted in 2 h at room temperature. The typical cyanidation process using 5 g/L of CN− at pH 10.5 on the same ore sample obtained 97% gold extraction in 24 h at ambient temperature. The gold extracted using DMSO was precipitated by adding a mild acidic solution, and the reagent can be recycled via distillation and reused in repeating cycles. The results show that DMSO can be used as a promising agent for gold leaching, offering a straightforward, cost-effective, and eco-friendly procedure with minimal chemical waste.

Assessment of Modified Culture Conditions for Fungal Bio-Oxidation of Sulfidic Gold Ores Performed at Circumneutral pH

The significant neutralization of waste streams required after the acidic bio-oxidation of sulfidic gold ores could be avoided by performing a novel treatment at circumneutral pH with an in situ neutralization. For the first time, the white-rot fungus Phanerochaete chrysosporium was incubated in a modified culture medium containing corn steep, an industrial waste product, to support microbial activity and, subsequently, the oxidation of a sulfidic ore at an initial circumneutral pH environment. In this investigation, the concentration of the native culture medium ingredients was first evaluated with response surface methodology to attain maximum sulfide oxidation. The statistical analysis proposed a modified culture medium composed of 12.86 g/L glucose, 2.20 g/L malt extract, 1.67 g/L yeast extract, and 0.49 g/L MgSO4·7H2O to reach a maximum of 28.7% sulfide oxidation after 14 d-bio-oxidation. pH-controlled batch cultures showed that an increase in initial pH in the range of 5.8 to 7.0 reduced the microbial activity, affecting sulfide oxidation. In addition, the modified culture medium at which yeast extract was substituted with 1.67 g/L corn steep produced comparable microbial activity and sulfide oxidation after 14 d, attaining 21.6% at 5% w/v with a maximum 39 U/L lignin peroxidase and 116 U/L manganese peroxidase. A 40.6% sulfide oxidation and 43.8% gold recovery were obtained after 42 d three-cycle replenishing bio-oxidation and 24 h cyanidation, respectively. Overall, corn steep waste showed the potential to substitute more expensive culture medium ingredients, supporting microbial activity and oxidation of sulfidic gold ores at an initial circumneutral pH and contributing to circularity of waste management.

Production of a Highly Concentrated Gold Solution from Aqua Regia Gold Leachate Using Sugarcane Bagasse Nanoparticles

This study produced a highly concentrated gold solution using nanoparticles (NPs) synthesized from sugarcane bagasse as an adsorbent for gold(III) recovery from an aqua regia gold leached lean solution. A 100 kg sample of gold ore collected from a mining site in Iperindo was concentrated. Mineralogical characterization and a fire assay test of the ore were carried out. Atmospheric and agitation leaching were conducted using aqua regia. Sugarcane bagasse NPs were prepared and used to study the gold(III) adsorption kinetics. Gold-loaded sugarcane bagasse NPs were desorbed in a 4 M aqua regia solution. The results revealed that the ore has a low water retention capacity which renders it friable. A microscopic examination established the presence of gold particles and pyrite in the ore. Ore leaching was eminently favoured by agitation yielding a weight loss of 6.3 % when an acid concentration of 4 M was used, the temperature was 90 ºC and the leaching time was 30 minutes. Synthesized nanocellulose was able to adsorb gold(III) from the leachate optimally with the following process parameters: 14 mL/g of adsorbent, 106.2 minute-long contact time, a temperature of 56 ºC and an agitation rate of 45 rpm when the concentration of leachate was 84 mg/L. The adsorption efficiency of the sugarcane bagasse NPs is comparable with that of commercial activated carbon, namely 92 and 95 %, respectively. The study concluded that NPs synthesized from sugarcane bagasse could be effectively used when upgrading gold and in purification processes.

Comparative characteristics of efficiency of pneumatic and pneumo-mechanical flotation machines in copper–gold ore processing

Comparative characteristics of efficiency of pneumatic and pneumo-mechanical flotation machines in copper–gold ore processing

Cyanidation of oxidized copper-bearing gold ore

Cyanidation of oxidized copper-bearing gold ore

Development and testing of selective agents for complex gold ore flotation

Development and testing of selective agents for complex gold ore flotation

Metasomatites of gold deposits and their connection with ore process of mountain Auminzatau (Central Kyzylkum)

The characteristics of mineral composition and features of metasomatic rocks of gold ore deposits of the Auminzatau mountains in the Central Kyzylkum are identified. The corresponding stages of ore mineralization are associated with certain types of metasomatites, which are their typomorphic features and reflect the features of the evolution of the stages and stages of a single mineral-forming system, which can be used as search criteria.

Mineralogy, fluid inclusion and stable isotope characteristics of the Inlice (Konya, Turkey) high sulfidation epithermal gold deposit: Implications for hydrothermal evolution and ore genesis

The Inlice high sulfidation epithermal gold deposit with 262,300 oz of gold ore is located in the Erenlerdağ-Alacadağ Volcanic Complex (EAVC) at the northern part of central Taurides. The volcanic succession of the study area is stratigraphically represented by andesite, block and ash flow, basaltic andesite lava flow and andesite lava flow. The deposit consists of seven neighboring mineralized veins termed Ana East, Ana West, West, Discovery, Güllü, Merkez and North Zone and is associated with an andesite (ca 8–9 Ma). Hydrothermal alteration from the innermost to the outermost parts of the deposit includes silicification, advanced argillic, intermediate argillic and propylitic. At the surface, quartz veins related to silicification are exposed as linear topographic relief trending mainly northwest-southeast and secondarily northeast-southwest and east-west. Deep drill core samples, including magnetite, quartz, biotite and anhydrite, imply the presence of potassic alteration in depth (50 to 970 m) possibly related to a porphyry Cu system. Ore assemblages are described as hypogene and supergene. The hypogene ore mainly includes pyrite (Py-I and Py-II) and enargite, and to a lesser extent chalcopyrite, sphalerite and marcasite. The supergene ore incorporates hematite and goethite, and minor covellite, chalcocite, malachite and native copper. Hypogene gold precipitation is associated with the mineral association of Py-II, chalcopyrite and enargite, while enargite mineral is a major host for gold (up to 600 ppm). Supergene oxidation resulted in the development of a secondary enrichment zone for gold (up to 14 g/t) extending to a depth of about 45 m.Microthermometric measurements show that the silicification associated with the mineralization was formed at homogenization temperatures ranging between 147 and 360 °C and salinities up to 6.5 wt% NaCl. This suggests that the fluid mixing and/or fluid dilution processes were important factors controlling the precipitation of gold. δ34S isotope compositions are between −0.9 and − 9 ‰, and further indicate a significant involvement of magmatic components into the hydrothermal fluids. Thus, it is concluded that at Inlice the hydrothermal fluids responsible for the alteration and mineralization processes were derived by relatively dilute fluids formed by the mixing of magmatic fluids with meteoric waters.

Typification of hydrogeological conditions in mineral deposits by system analysis method

The paper presents a non-standard approach to the typification of mineral deposits in Eastern Siberia (Russia) according to hydrogeological conditions under insufficiency and unevenness of the initial information. The most rational way to solve this problem at initial research stages is to identify a number of easily determined indirect indicators that determine the selection of sites promising for drilling hydrogeological wells. The author uses the method of system analysis including two main stages of analysis and synthesis, which result in the typification of the objects under study in accordance with the assigned tasks. The developed methodology is used for various purposes: structural hydrogeological zoning of the Ilim-Lena plateau with associated main iron ore deposits of Eastern Siberia, typification of alluvial deposits of the Lena gold ore region according to the complexity degree of engineering hydrogeological conditions, identification of the sites with high water abundance in the oil and gas fields of Eastern Siberia.

Endogenous gold of the russian Altai

The Altai of Russia in the geological and metallogenic sense includes the Altai Mountains and the northwestern part of Rudny Altai, and in administrative terms - the Altai Territory and the Altai Republic. Gorny Altai has experienced a complex history of geological development, including subduction, accretion-collision and rifting processes with the formation of various types of magmatism and endogenous gold mineralization. The history of gold mining in the region is associated mainly with placers and currently the reserve of placer gold deposits is almost exhausted, and the prospects for primary mineralization have been little studied. In this regard, the problem of assessing the potential of ore gold in known ore occurrences and promising areas of ore clusters has become urgent in the region.In the Russian part of Rudny Altai, gold reserves are mainly associated with gold-bearing pyrite-polymetallic deposits and less with small gold ore occurrences.Gold-sulfide-skarn, epithermal gold-silver, copper-gold-porphyry and gold-mercury types of mineralization may have important practical significance for the region. The increase in ore gold reserves in the Russian part of Rudny Altai is mainly due to additional exploration of pyrite-polymetallic deposits.

Research and development of gold ore processing technology

This paper presents the results of technological studies of two samples of gold-bearing ore from the gold-bearing deposit of Kazakhstan deposits 1 and 2. A comprehensive analysis of ore samples by X-ray fluorescence, X-ray phase, chemical, and mineralogical methods was carried out. The calculated initial gold content was determined, and X-ray fluorescence analysis showed that the main elements that make up the ore are oxygen up to 51% and silicon up to 33%. X-ray phase analysis showed the presence of more than 95% quartz and muscovite in the samples. The form of finding gold in the ore, according to the results of mineralogical analysis, is defined as free gold and gold in iron hydroxide. Silver is present in the studied samples in the form of various types of halides. An ore beneficiation scheme has been developed and presented, including gravity and flotation. Gravity enrichment was carried out in two stages, with the production of concentrate and tailings, with the maximum recovery of gold in concentrate up to 91%, flotation enrichment using butyl xanthate reagents and a blowing agent, was carried out in two stages with the production of main and control concentrates and final flotation tailings. The subsequent hydrometallurgical study of the ore was carried out to assess the effect of sodium cyanide on the extraction of gold, tests were performed on the leaching of the initial samples of the ore and the obtained flotation and gravity concentrates in the agitation mode, it was found that cyanide leaching is an effective method for processing the mineral raw materials of the gold-bearing deposit of Kazakhstan, and the obtained flotation concentrates, with the recovery of gold into solution under optimal conditions up to 98%. The results obtained make it possible to predict the effectiveness of the main technological stages in the ore processing scheme, technology optimization, and maximum gold recovery.

Development of Regression Model and Optimization of Mechanical Properties of Geopolymer Concrete Prepared Using Gold Ore Tailings

Development of Regression Model and Optimization of Mechanical Properties of Geopolymer Concrete Prepared Using Gold Ore Tailings

Physicomechanical Properties and Characterization of Gold Ore Tailings and the Utilization in Manufacturing of Geopolymer Concrete with Class F Fly Ash and Recycled Coarse Aggregates

Physicomechanical Properties and Characterization of Gold Ore Tailings and the Utilization in Manufacturing of Geopolymer Concrete with Class F Fly Ash and Recycled Coarse Aggregates